Because the superconductor MgB2, which was discovered in Japan in 2001, has the most superior superconducting critical temperature (39 K) among the metal-based superconductors, and it is relatively easy to manufacture the bulk materials and to process the wire, research and development of this superconductor and of forming its wire is undertaken all over the world. A method of manufacturing the bulk materials generally includes pressurizing a mixed powder of Mg powder or MgH2 powder and B powder and then heat-treating (sintering). One of the major methods of forming the wire is a powder-in-tube method wherein a metal tube is filled with Mg (MgH2) powder and B powder. However, Jc characteristics of the bulk form and the wire which are manufactured by the ordinary powder-sintering method and by the powder-in-tube method are not very high. Accordingly, in order to improve the Jc, there have been attempts to add various types of impurities into the mixed powder. Among these additions of impurities, the addition of SiC fine particles having a particle size at the nanometer level is most effective, and much research on this addition is being undertaken (S. X. Dou, et al., Journal of Applied Physics 94 (2003) 1850 (Document 1). However, the price of the SiC fine particles is high and has been an obstacle to putting this technique into practical use.